Kanye West was behind six of the 10 most valuable sneakers last year, according to High Snobiety and sneakerhead data site Campless. His YEEZY Boost Adidas sneakers are among the most coveted in the world. And anyone who has got their hands on them did quite well—provided they haven’t actually been worn.

The YEEZY Boost 750 “Triple Black” is the most expensive in the range, with an average “deadstock” (meaning as new, still in the box) price of $1,876 on eBay at the end of 2015. The shoes sold at a retail price of $350—meaning that you could have made a return of 436% almost instantly. The man known as Yeezus was only slightly exaggerating when he said last year:

People saying, “Ye, Ye, take it easy”
20 Gs for the YEEZYs off of eBay

And those sneakers were only released in December. You would be hard pressed to find another asset that gained as much value last year; stocks were mixed, bonds went sideways, and commodities were hit hard. Gold, the traditional safe haven in times of turmoil, fell by more than 10% during the year.

Why are West’s sneakers doing so well? In short, scarcity. YEEZYs are extremely hard to come by—so much so that GQ recommends you enter raffles to get a pair when they come out. The second-most valuable sneaker is a special Nike Air released exclusively in China.

Another crazy thing is that only one Air Jordan made the top 10 in the Campless list last year—an incredible coup for West, given that Michael Jordan’s shoe brand is historically beloved by sneakerheads. Then again, West did once say:

Hold up, I ain’t trying to stunt, man
But the Yeezys jumped over the Jumpman